Short answer: the passphrase wins. Password strength comes from entropy — roughly, length times unpredictability — and a passphrase of four or more random words has far more of it in practice than a short password full of symbols. Length beats complexity, every time.
The math: length beats complexity
Every extra character multiplies the number of possible passwords. Widening the character set (adding symbols) helps a little; adding one more character multiplies the possibilities by the entire set size. Run the numbers and the gap is clear:
// Theoretical entropy: length × log2(pool size)
const entropy = (length, pool) => length * Math.log2(pool);
entropy(10, 94); // random 10-char password: ≈ 66 bits (strong — but nobody memorizes these)
entropy(4, 7776); // 4 random diceware words: ≈ 52 bits (strong AND memorable)
// The catch: "P@ssw0rd!" is not random. Attackers try dictionary words
// with predictable substitutions first, so its real entropy is a
// fraction of the theoretical 66 bits. Random words stay random.Why P@ssw0rd fails
Leet-speak substitutions (a→@, e→3, o→0) feel clever, but password crackers have known every one of them for decades — they are baked into the dictionaries attackers try first. "P@ssw0rd!" is a dictionary word wearing a costume. A password's strength is not how strange it looks to you; it is how unpredictable it is to someone guessing systematically. Four genuinely random words have no pattern to exploit, which is exactly why they hold up.
The traps
- Complexity theater: "P@ssw0rd!" looks strong and is weak. Unpredictability is what matters, not the symbol count.
- Reusing one good password: a strong password used on ten sites is ten sites' worth of risk. One breach exposes all of them.
- Predictable "random" words: a passphrase only works if the words are actually random — song lyrics and famous quotes are in the dictionaries too.
- Skipping 2FA: even the strongest password can leak. Two-factor authentication means a stolen password alone is not enough.
- Storing passwords in plaintext notes: if you have to write them down, use a password manager — that is what it is for.
What to actually do
Generate a passphrase of four or more random words for the accounts you type by hand, use a password manager to generate and store a unique random password for everything else, and turn on two-factor authentication wherever it matters — email and banking first. You only need to memorize one strong master password; the manager remembers the rest.
Try it
Generate a strong passphrase or a random password with the Password & UUID Generator — everything is created locally in your browser, nothing is sent or stored anywhere.